use strict;
use warnings;
use 5.032;          # chained comparison

use Term::ANSIScreen;
use GD;

use if $^O eq 'MSWin32', 'Win32::Console'; 
my $OUT;
if ( $^O eq 'MSWin32' ) {
    $OUT = Win32::Console-> new( STD_OUTPUT_HANDLE );
    $OUT-> OutputCP( 65001 );
    $OUT-> Mode( $OUT-> Mode | 4 );
}

my @shades = (
    "\N{SPACE}", "\N{LIGHT SHADE}", "\N{MEDIUM SHADE}", 
    "\N{DARK SHADE}", "\N{FULL BLOCK}"
);
utf8::encode( $_ ) for @shades;

my @hues = <red yellow green cyan blue magenta>;
my @chars;

my $source = GD::Image-> new( 'rose.png' ) or die;
my $dest   = GD::Image-> new( 1, 1 ) or die;

BLOCK1:                     # 5 neutral grays
for my $s ( 0 .. $#shades ) {
    $dest-> colorAllocate(( 255 / $#shades * $s ) x 3 );
    push @chars, colored( $shades[ $s ], 'white' )
}
BLOCK2:                     # 24 = (6 hues) * (4 shades)
for my $h ( 0 .. $#hues ) {
    for my $s ( 1 ..$#shades ) {
        $dest-> colorAllocate(
            map { $_ / $#shades * $s * 255 } 
                ( 0 <= $h <= 1 || $h == 5 ),                # R
                ( 1 <= $h <= 3 ),                           # G
                ( 3 <= $h <= 5 )                            # B
        );
        push @chars, colored( $shades[ $s ], $hues[ $h ])
    }
}

for my $y ( 0 .. $source-> height - 1 ) {
    for my $x ( 0 .. $source-> width - 1 ) {
        my $rgb = $source-> getPixel( $x, $y );
        my ( $r, $g, $b ) = $source-> rgb( $rgb );
        
        print $chars[ $dest-> colorClosestHWB( $r, $g, $b )]
    }
    print "\n"
}